Sun vs fossil fuelsIn 1973 in Italy, after the energy crisis, we began looking carefully on thesun as an alternative source for the production of electricity.In these last years, globalIn these last years, globalwarming is changing thewarming is changing theclimatic conditions of ourclimatic conditions of ourplanet.planet.The European Council hasThe European Council hasbegun to provide incentivesbegun to provide incentivesfor renewable and cleanfor renewable and cleanforms of energy which doforms of energy which donot involve any kind ofnot involve any kind ofemissions in theemissions in theatmosphere.atmosphere.
Renewable energies: forms of energy produced from renewable sourcesthat can regenerate at least at the same speed they are used or aren’t “ exhaustible “in a “human” time scale.Their use doesn’t affect natural resources for the futuregenerations and are clean energies, not polluting.Solar energy is the energy associated withsolar radiation and it represents the primarysource of energy on the Earth and it makeslife possible.The sun irradiates the terrestrial surface with50 milion GWATT every moment.Nearly all other other available energysources derive from this energy, such as: fossilfuels, wind, water, biomass, tides.
The covered areaneeded to provide theenergy equivalent to thecurrent primary energydemand is indicated bythe dark disks.SOLAR ENERGY GLOBAL RESOURCESThe colours on the map show the average solar power that reaches the Earth, alsotaking into account cloudiness indicated by weather satellites.TW (tera watt ) = 1012WTwe (tera watt energy)The scale is in WATTper square metre.
Advantages It is renewable. It is a free, clean and unlimited source. It does not produce pollution because itdoes not burn materials which releasetoxic gases in the atmosphere. It reduces the consumption of fossil fuels. It increases the economic value of ahouse. It sets in motion an economic sector whichis doing well (Green Economy). its systems are strong (25 yearswarranty). It has low maintenance costs. It has a system of modular installation.• Harmful disposal.• Discontinuous production.• Not very high efficiency.• High surfaces occupied.• High initial costs.DisadvantagesEnergy fromthe sun
Solar energy useSolar energy can be used in many ways, the most used are solar cells and solarpanels.Solar thermal panels can be:- for domestic use to produce hot water in small home plants.- for industrial use to produce steam to generate electricity.Photovoltaic panels are used:For domestic and industrial use to produce electricity directly.Domestic use
Natural circulationthermal solar panelsNatural circulation thermal solar systems are so calledbecause they exploit hot liquids properties to rise in anatural way.(A) Sunbeams heat transfer fluid (water + antifreeze) whichrises naturally up to the tank placed horizontally abovethe panels.(B) The liquid transfers its heat to the water inside the tankand enters the hydraulic water circuit of the house1) Valve2) Storage tank3) Insertion pipe4) Absorption panels5) Cold water insertion pipe.Diagram of a solar panel
Augusto Righi was an Italianphysicist of Bologna and hewas the first to recognize thisphenomenon in 1888even if you had to wait the writingsof Einstein for a formalization of thephysical principle.The photovoltaic principleThe photovoltaic principle
Photovoltaic TechnologyUsing semiconductors, solar PV modules createpower by converting sunlight into electricity.The semiconductor material most commonly usedfor the construction of photovoltaic cells is silicon.The silicon is found in natureSurely the material most often used is crystallinesilicon, one of the most common chemical elementsin the earth crust.Other materials used for the construction ofphotovoltaic cells are: copper, indium, diselenide,cadmium, tellurideTo coat and protect the thin layers of semiconductormaterial, most of the photovoltaic technologies useglass.Approximately 80% of the weight of a module ismade of glass.
Every cell consists of two main layers: one charged positivelyand the other negatively.A photovoltaic panel is made of some tens ofsilicon cells connected by conductor jointsThis produces a steady electromagnetic field within the cellwhich conveys the flux of electrons.The aluminum and silicon dioxide layers constitute theelements of the circuit itself, allowing the current transition.A photon which interacts with the atoms of the positive layerarrives (the anti-reflecting layer favours the input) freeing anelectron that is conveyed to the circuit:WE HAVE THE CURRENT.The photovoltaic principleThe photovoltaic principleThe capability of photons to extract electrons from atomsThe capability of photons to extract electrons from atomsis calledis called photoelectric effect.photoelectric effect.E
The most common version of aphotovoltaic cell is constitutedby a lamina of semiconductormaterial, the most widespreadof which is silicon, and it isgenerally blue or black.Small amounts of siliconphotovoltaic cells are found incalculators, watches etc..The photovoltaic cell efficiencyis obtained by evaluating theratio between the electricalpower produced by the cell andthe energy of the solarradiation that invests the entiresurface .PHOTOVOLTAIC CELL
SOLAR POWERINSTALLATIONWhen photons (particles ofSun energy) strike aphotovoltaic cell, a part ofenergy is absorbed by thematerial and some electronsflow through thesemiconductor material(suitably treated) producingdirect currentfotone Elements of aphotovoltaic plant:CELLAMODULOPANNELLOSTRINGACAMPOCELLMODULEPANELSFIELDSTRINGS
SOLAR TRACKING PHOTOVOLTAIC PLANTSolar tracking is a technology able to increase considerably the production ofelectric power from photovoltaic panels.Efficiency can increase by 45%The tracking of the sun can be made with a single axle (in this case rotationtakes plase only on the horizontal, or vertical, axle) or with a double axle,that is rotation takes place both horizontally and vertically at the same time.In this second way the panels are always head-on the Sun.
The process to extract and work silicon is very expensive.We need to limit the costs of production and sales and develop new technologiesin the futureStrategies for the future:Expand silicon.Researchers at Stanford University ,in California, have developed a silicon-based chip which can bemechanically expanded ("stretchare" in U.S. slang, means stretching the chip in every direction) in orderto cover a wider area. This chip can be up to hundreds of times the original size.Use nanotechnologies.“Nanosolar “produces third generation photovoltaic cells obtained by pressing nanoparticles made ofcopper, indium, gallium and selenium alloy on flexible material (CIGS: their efficiency is quite the sameto the one of silicon, but their cost is approximately about a fifth, which is lower even than theexploitation of coal) with a new "ink energy" able to transform solar radiation into electrical energy .Concentrate sunlight (CPV tecnhology).“Emcore Corp”, from Canada, a provider of solar stations and space communications systems, haslaunched the application of advanced technologies on the Earth. These were tested only out of theatmosphere before. In this type of cells the concentrator has the size of 1 square centimeter, able togenerate the same energy of 500 square cm of conventional solar cells. The materials used for theconstruction of the concentrator are cheap.
Most of a solar module componentscan be reused.Thanks to technological innovationsoccurred in recent years , up to 95 % ofsome semiconductor materials or glass,as well as vast quantities of ferrous andnon-ferrous metals used in photovoltaicmodules can be recycled.However, the percentage of photovoltaicmaterial which is unused or disposed inlandfills not suitable for this purpose is stillvery high.Furthermore, during the disposal process,with the only exception of certainmaterials which do not contain toxicsubstances in their composition, heavilypolluting substances from the constituentmaterials are released into theatmosphere.Recycling panelsTHE MAIN OBJECTIVE OF PVCYCLE is to recycle 80% (inweight) of a solar module by2015 and 85% by 2020From 1° July 2012 photovoltaicpanels producers must have themembership certificate of anauthority that ensures the recyclingof photovoltaic modules.In the absence of such membership,proved by its certificate to bepresented at the time of sale, themanufacturer cannot allow hiscustomers to take advantageof state incentives
The largest active installation islocated in California, near LosAngeles.It has 118 large panels that exploitthe desert sun producing 250 MWpower.This solar power installation is goingto reach its maximum power in 2014.It will increase by 50% the total flowof solar power plants installated inthe U.S.A. using the “linear parabolicmirror” concentration technology.It will be able to cover theconsumpition of 54,000 homes.Concentration Photovoltaic Installations inCaliforniaThe mirrors are concave and at least10 metres long.The Sun radiation which reaches them isconcentred on a pipe put on their focus.
A photovoltaic installation inCremona: in 2011 it produced5789,257 kwh electricity forthe National Electric system,net of its own use.In Europe, the mainphotovoltaic power installationis located near Gargano in thesouth of Italy and extendsover an area of 4000 squaremeters.
It is made of one or more satellites whichconvert sunlight into electricity throughphotovoltaic cells.Then they transmit the energy thus obtainedin the form of microwaves or laser throughan antenna.The advantage consists in the constancy oflighting and in the lack of weather conditions(clouds, rain, etc.) which can reduce the flowof energy.An orbital solar power station is a hypothetical electric power plant
An orbital solar power station ismade of three parts:• a big solar energy collector withphotovoltaic cells.• an aerial to transmit microwawestowards the earth.• a high dimension aerial on theEarth that receives microwawesand changes them into electricenergy.With a solar power station in spacewe would receive direct, constantlighting with 99% efficiency.
A big problem will be sendingmaterials into orbit. Taking intoaccount the current cost of spaceshuttle, the transport is beetwen8.000 and 11.000 U.S. dollars per kg.The exact price will dipend on thenumber of launches necessary to sendmaterials into orbit.This way to acquireenergy is just at theexperimental stageat present.For the future,scientists are lookingfor new systems totransmit lasers tothe Earth, able toovercome technicaland economicalobstacles.
The mostsustainable city..In 2010 the Economist Intelligence Unit (EIU) designatedCopenhagen as the most ecologically sustainable Europeancity.The British Unit has measured the commitment of 30 citiesin 30 countries in riducing the environmental impact,analyzing 7 sustainability aspects:• level of carbon dioxide emissions• energy consumed•sustainability of buildings•system of transport•use of water•disposal of rubbish•use of territory
The aim is to improve cities withsustainable technologies that enable:• An intelligent managment of cartraffic;• The development of Smart grids(they conduct the electric system)which can develop the use ofrenewable energies;• The development of Smart buildings(with reduction of energy andemission of CO2);SMART CITY: re-thinktoday’s townsTechnologies have a more and more important role in ourcities and will become an element of daily and spontaneoususe for citizens.From now to 2020 Italian cities that want to become “Smart” will get state incentives.A percentage of these incentives is intended for young people aged under 30 who wantto present social innovation projects.
Low2No has been developing andgrowing for three years: a 100%sustainable area (zero impact) builtnear Helsinki.Finland is, despite the small numberof its inhabitants, slightly more than5 million, the third nation in theworld for Co2 emissions. It issurpassed only by the United Statesof America and United ArabEmirates.A company from Turin won the callfor bids in September 2009. It willexclusively use solutions made inItaly.Low2No is a project which involves severaleconomic sectors with "smart services”.
The amount of CO2 produced duringdaily activities by a family has beenkept under control like a diet.The Webster family,who lives in Espoo(Finland) was the protagonist of anexperiment lasted one year anddocumented in the film "Recipes fordisaster"(http://www.youtube.com/watch?feature=player_embedded&v=qlm6GvxdlRE)The documentary showed how it is possible to adopt a low-footprint lifestylewithout giving up our habits and nice things life can offer.Giving up plastic products or cars is undoubtedly a difficult choice to be taken, butabsolutely possible, especially if adopted by a group of people.We can see how two children are able to cope with the new plastic-free life withenergy and enthusiasm.Low2No wants to promote a more sustainable lifestyle.
The choice to adoptthe metaphor of"Detox Diet"worked.John Webster andhis family, after ayear characterizedby challenges,difficulties, doubtsbut alsosatisfactions andsmall everyday joys,can effectivelyreduce drasticallythe “homeproduction” of Co2.
THEY HAVE BEEN INSTALLEDLAYING ON A TERRACE:one planton S. FrancescoPRIMARY SCHOOLLAYING RETROFIT:two plantsOne on G. SacconLOWER SECONDARY SCHOOLOne on S. FrancescoPRIMARY SCHOOLPhotovoltaic PlantsTHE TOWN OF S.VENDEMIANO HAS INSTALLEDPHOTOVOLTAIC PANELS WITH POWER UP TO 20KwpON OUR SCHOOLS
LOWER SECONDARYSCHOOLTHE PANELS CAN ONLY BE GLIMPSED FROM BELOW“Retrofit” laying on the roof
PHOTOVOLTAIC PLANT DIAGRAMPHOTOVOLTAIC MODULES INVERTER METERUSERSEXCHANGE/SALE METERSNATIONALELECTRIC SYSTEMDISTRIBUTIONELECTRIC LINEDIRECTIN OF ENERGY FLOW FROM THEELECTRIC SYSTEMDIRECTION OF PHOTOVOLTAICENERGY FLOWit turns the direct currentdelivered by the sisysteminto alternate current toput it in the electricsystem
KWH of ENERGYPRODUCED ATTHE MOMENTKWH of ENERGYPRODUCED UNTILTHAT TIMECO2 NOT PRODUCED ANDNOT RELEASED IN THEATMOSPHEREGRID_CONNECTED: connection to thenational electric system. The energyproduced is transferred into the nationalelectric system and calculated by theoperator. This one can purchase the energyproduced or allow us to use it whennecessary. In this case, there are stateincentives which allow us to amortize thecost of the plant.INDICATOR DISPLAY INSTALLED IN THE HALLS OF SCHOOLS
Class 3CStudents BAGHIU DIANA BARRO DANIELE BASEI NICOLE BOLDRIN ELENA BONETTO PATRICK BOLZAN ALESSANDRO CASAGRANDE MARCO CARIA IVAN DAL PONTE ELISABETTA DA RIN FIORETTO STEFANO DE ZAN TOBIA ESPOSITO SAMUELE FLAVIANI DEBORA GIACOMIN GIOIA HU ANGELO ISEPPI ANASTASIA TRENTIN OSCAR SCUDELLER GIOIA ZORZINI LORENZOTeachers:Silvana SorceGabriella De Pizzol